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Accident description
Last updated: 23 October 2017
Status:Final
Date:Friday 12 February 2016
Time:ca 07:00
Type:Silhouette image of generic C130 model; specific model in this crash may look slightly different
Lockheed L-100-30 Hercules
Operator:Lynden Air Cargo
Registration: N401LC
C/n / msn: 4606
First flight: 1975
Total airframe hrs:55393
Cycles:35421
Engines: 4 Allison 501-D22A
Crew:Fatalities: 0 / Occupants: 5
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 0 / Occupants: 5
Airplane damage: Substantial
Location:near Iliamna, AK (   United States of America)
Phase: En route (ENR)
Nature:Cargo
Departure airport:Bethel Airport, AK (BET/PABE), United States of America
Destination airport:Anchorage-Elmendorf AFB, AK (EDF/PAED), United States of America
Flightnumber:LYC401
Narrative:
A Lockheed L-100-30 Hercules transport plane, operated by Lynden Air Cargo, diverted to Iliamna Airport, Alaska following a rapid in-flight decompression.
The aircraft departed Bethel, Alaska at 06:50 hours local time on a flight to Elmendorf Air Force Base near Anchorage. The airplane climbed to the planned cruising altitude of FL250. At 07:11, upon reaching 24500 feet, there was an in-flight decompression. The flight crew initiated an emergency descent to FL120, which was reached at 07:16 hours. The flight then diverted to Iliamna were a safe landing was carried out at 08:05 hours.
Examination of the airplane revealed a large hole in the forward pressure bulkhead canted web.

The next day the aircraft was ferried to Anchorage and from there to Kelowna, BC, Canada at an altitude of 10000 feet.

Probable Cause:

PROBABLE CAUSE: "The fatigue failure of the forward pressure bulkhead canted web that originated from stress corrosion cracking areas. Contributing to the failure were inspection procedures and intervals inadequate to identify the crack."

Classification:

Forced landing on runway

Sources:
» NTSB
» Flightaware


Follow-up / safety actions
The manufacturer released a Service Bulletin based on the findings of the investigation to provide more detailed instructions and updated intervals to inspect for cracking of the forward pressure bulkhead canted web.

Photos

photo of Lockheed L-100-30 Hercules N401LC
flight route
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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Bethel Airport, AK to Anchorage-Elmendorf AFB, AK as the crow flies is 645 km (403 miles).

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